Store access_tokens in the DB

src/github.com/matrix-org/go-neb/realms/github/github.go

@@ -7,6 +7,7 @@ import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/matrix-org/go-neb/database"
 	"github.com/matrix-org/go-neb/types"
+	"io/ioutil"
 	"net/http"
 	"net/url"
 )
@@ -19,10 +20,11 @@ type githubRealm struct {
 }
 
 type githubSession struct {
-	State   string
-	id      string
-	userID  string
-	realmID string
+	AccessToken string
+	Scopes      string
+	id          string
+	userID      string
+	realmID     string
 }
 
 func (s *githubSession) UserID() string {
@@ -76,6 +78,7 @@ func (r *githubRealm) RequestAuthSession(userID string, req json.RawMessage) int
 }
 
 func (r *githubRealm) OnReceiveRedirect(w http.ResponseWriter, req *http.Request) {
+	// parse out params from the request
 	code := req.URL.Query().Get("code")
 	state := req.URL.Query().Get("state")
 	logger := log.WithFields(log.Fields{
@@ -83,19 +86,49 @@ func (r *githubRealm) OnReceiveRedirect(w http.ResponseWriter, req *http.Request
 	})
 	logger.WithField("code", code).Print("GithubRealm: OnReceiveRedirect")
 	if code == "" || state == "" {
-		w.WriteHeader(400)
-		w.Write([]byte("code and state are required"))
+		failWith(logger, w, 400, "code and state are required", nil)
 		return
 	}
 	// load the session (we keyed off the state param)
 	session, err := database.GetServiceDB().LoadAuthSessionByID(r.ID(), state)
 	if err != nil {
-		logger.WithError(err).Print("Failed to load session")
-		w.WriteHeader(400)
-		w.Write([]byte("Provided ?state= param is not recognised.")) // most likely cause
+		// most likely cause
+		failWith(logger, w, 400, "Provided ?state= param is not recognised.", err)
 		return
 	}
-	logger.WithField("user_id", session.UserID()).Print("Mapped redirect to user")
+	ghSession := session.(*githubSession)
+	logger.WithField("user_id", ghSession.UserID()).Print("Mapped redirect to user")
+
+	// exchange code for access_token
+	res, err := http.PostForm("https://github.com/login/oauth/access_token",
+		url.Values{"client_id": {r.ClientID}, "client_secret": {r.ClientSecret}, "code": {code}})
+	if err != nil {
+		failWith(logger, w, 502, "Failed to exchange code for token", err)
+		return
+	}
+	defer res.Body.Close()
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		failWith(logger, w, 502, "Failed to read token response", err)
+		return
+	}
+	vals, err := url.ParseQuery(string(body))
+	if err != nil {
+		failWith(logger, w, 502, "Failed to parse token response", err)
+		return
+	}
+
+	// update database and return
+	ghSession.AccessToken = vals.Get("access_token")
+	ghSession.Scopes = vals.Get("scope")
+	logger.WithField("scope", ghSession.Scopes).Print("Scopes granted.")
+	_, err = database.GetServiceDB().StoreAuthSession(ghSession)
+	if err != nil {
+		failWith(logger, w, 500, "Failed to persist session", err)
+		return
+	}
+	w.WriteHeader(200)
+	w.Write([]byte("OK!"))
 }
 
 func (r *githubRealm) AuthSession(id, userID, realmID string) types.AuthSession {
@@ -106,6 +139,12 @@ func (r *githubRealm) AuthSession(id, userID, realmID string) types.AuthSession
 	}
 }
 
+func failWith(logger *log.Entry, w http.ResponseWriter, code int, msg string, err error) {
+	logger.WithError(err).Print(msg)
+	w.WriteHeader(code)
+	w.Write([]byte(msg))
+}
+
 // Generate a cryptographically secure pseudorandom string with the given number of bytes (length).
 // Returns a hex string of the bytes.
 func randomString(length int) (string, error) {